Monday, 22 August 2011

Building my own Delphi Physics Engine part IX

I'm quite familiar with GDI, the graphics provided under Microsoft and which is widely used in Windows applications. TDPE is now ready to use Direct2D as now it's fully supported by Delphi 2010 and XE. According to MSDN, Direct2D is: a hardware-accelerated, immediate-mode, 2-D graphics API that provides high performance and high quality rendering for 2-D geometry, bitmaps, and text. The Direct2D API is designed to interoperate well with GDI, GDI+, and Direct3D.
As I'm testing this under Windows Vista, I've had to upgrade my windows version to Service Pack 2 and then I've installed the following update (KB971512 - The Windows Graphics, Imaging, and XPS Library contain the latest advancements in modern graphics technologies for gaming, multimedia, imaging and printing applications.). Direct2D is already installed in Windows 7.

We can use the same methods from TCanvas for our TDirect2DCanvas as they derive from the same ancestor TCustomCanvas. But you need to check the documentation for differences in the way they work.

A simple way to use Direct2D is as follows:

    Direct2D, D2D1;

procedure Paint();
    if TDirect2DCanvas.Supported then
        d2dCanvas := TDirect2DCanvas.Create(Canvas, ClientRect);
            // drawing goes here

Here is the result of the Physics Engine using a Direct2D Render and a GDI Render:

You will see the difference when switching from GDI to Direct2D as the performance is quite different. When it comes to Direct2D, my computer is getting quite slower as my graphic card is not powerful at all and we can see that it takes a while to render the image.

GDI uses Pixel graphics but Direct2D can supports vector graphics as well, in which mathematical formulas are used to draw the lines and curves. Vector graphics provides high quality rendering independent of resolution of the device, while the pixelated graphics has dependency with resolution which may results in choppy graphics.

Most of the GDI APIs are not using anti-aliasing and transparency. Ofcrouse there are functions to do so but always there’s programming cost for taking advantage of these features. Also if we apply transparency and anti-aliasing, the computations are done using CPU. Direct2D can take advantage of graphics hardware and delegate the computationally intensive tasks to GPU

Get the latest version here: ThundaxBallDemo v1.584.
'd' will drop a box with a random colour and a constant angular velocity.
'f' will drop a circle with a random colour and a constant angular velocity.
'mouse interaction' mouse is able to grab items.
'q' Enable/Disable GDI or Direct2D rendering.

Note: You need to have installed Direct2D to run the app using Direct2D, otherwise GDI will be used.

Related links:


  1. Direct 2D is perform on marketing papers, but perfs are not always here... A common performance issue with Direct 2D is that the graphical card drivers are not optimized for it. Even without anti-aliasing, Direct 2D is slower than GDI! Perhaps you could use your own "PolyLine" version, as stated by

  2. Hi Arnaud,
    Thanks for your comment. I'll give a try to your suggestion, I'm sure it will improve quite a bit using PolyLine instead of predefined shapes.


  3. Nice job Jordi. D2D is awesome but starts to hick up after a few hundreds of primitives in Delphi canvas. Works just fine on Win32 C WinAPI application. Pitty, it's such a powerful framework.

    1. Thanks!. I know D2D is quite good but after loading few primitives it gets really slow.